[Numpy-discussion] Selecting columns of a matrix

[Bill Baxter]

On 6/21/06, Simon Burton <simon at arrowtheory.com> wrote:
>
> On Wed, 21 Jun 2006 13:48:48 +0900
> "Bill Baxter" <wbaxter at gmail.com> wrote:
>
> >
> > >>> a[:,num.where(v>0.5)[0]]
> > array([[1, 2, 4],
> >        [6, 7, 9]])
> >
> > I'll put that up on the Matlab->Numpy page.
>
> oh, yuck. What about this:
>
> >>> a[:,num.nonzero(v>0.5)]
> array([[0, 1, 3],
>        [5, 6, 8]])
> >>>


The nonzero() function seems like kind of an anomaly in and of itself.    It
doesn't behave like other index-returning numpy functions, or even like the
method version, v.nonzero(), which returns the typical tuple of array.  So
my feeling is ... ew to numpy.nonzero.

--Bill
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